AVR300/27A - analog input is noisy

[tvh3ad]

If you've read any of my previous posts, you'll know that I'm basically very happy with my AVR300/27A combo. That said, I have a minor problem with background noise which I would like to get resolved. The noise is noticeable at relatively high gain (say, 75 db) with quiet source material (and when nothing is being played).

Some info:

- With everything connected, the noise is present on all inputs...it's worse on analog inputs than digital but is not absent on any of them.

- I removed all cabling except speakers and found that the noise was completely gone, so I suppose that rules out the AVR300 as the source.

- I began recabling, starting with the subwoofer, then moving to the DVD recorder, the VCR, etc.

- I found that the VCR was the main culprit and subsequently re-routed its outputs through the DVD recorder.

- With the VCR removed, the amp stays silent even at maximum gain UNTIL I recable the 27A. The digital output is fine, but if I connect even a single analog cable (I have 8, 6 for DVD-A and 2 for stereo), the noise level increases. It's not as bad as it was before, but it's definitely still there. The interconnects are decent (MIT for the fronts, blue jeans for the others) and the problem occurs regardless of which cable is connected, so this would seem to rule out the physical cables.

- The ground lift switch has no effect.

So...I'm stumped. Any theories? Ideas?

Thanks.

[roffe]

I am not sure if 27A is a CD player or what, but have you tried Stereo Direct? Is it still noisy?

[Hifi addict]

just a thought (it will not completely remove the noise, but lower it) is to phase check your powerconnections.

Have all your devices connected to the poweroutlets in a way that the least amount of voltage is found on the connectors.
This will lower the voltage difference between the devices and thus the noise levels/some of the ground issue's

[roffe]

BTW... If there is a TV set near the setup, try to turn it off with the power switch (don't use the standby-mode). This is a source of noise in my setup, and I never have the TV turned on when listening to music. In addition to that, I don't use the AVR300 for video switching. For me, the AVR300 is a pure audio component.

[tvh3ad]

I have tried just about everything -- ground lift, phase check, etc., and I still can't get rid of the noise. Next step is to try swapping the 27A with my CD72; if that shows a clear noise issue with the 27A, it goes to the shop. If not...???

[Hifi addict]

what software and dsp version are you using ? the latest DSP version changed some level settings and (it's a long shot) possible some noise levels??

[tvh3ad]

I'm on the latest release of both. Haven't had time to do any component swapping but am hoping to get back into it this evening.

[tvh3ad]

Borrowed a DV79 from my local Arcam dealer last night & swapped it with my 27A. No change in the noise! My dealer says that the next step is to look at cleaning up the AC via some kind of device to see if that has any effect. This is a whole new world for me, but perhaps noise is to be expected when you add video to the equation...or perhaps I'm just used to the (inaudible) noise floor of my stereo rig & my expectations are too high?

I dunno, but I do know that after spending a gazillion dollars on my HT, I want the audio to be darn near flawless and it ain't there yet...

[tvh3ad]

If anyone is interested, here's the final outcome:

- I'm not sure how I missed this in my first few rounds of troubleshooting, but it turns out that most of the noise was being caused by the coax digital output from a Sony DVD recorder. Even with the unit unplugged and disconnected from everything else, it still generates noise! I also tried grounding the unit's chassis directly to the AVR300 but with no improvement. Switching from coax to toslink kills the noise off nicely, so I now have a workaround if not actually a solution.

- I borrowed an EquiTech AC power balancer over the weekend from my local gearhead shop as part of the debugging process. It did absolutely nothing for the problem being caused by the Sony...but if you've never tried one of these (I hadn't), you might be surprised at the difference it makes both with sound and video: it's like getting a whole new rig. Too bad it goes back to the shop tomorrow...

[Hifi addict]

try using a other or "better" coax cable. I guess your cable's ground is short circuiting everything. A good cable should have the ground only connected to 1 connector and not both to overcome this issue.

[tvh3ad]

I thought of that, but in this case I'm pretty sure it's the Sony unit itself. The original cable was a monster digital coax, and I also tried swapping it with the bluejeans coax I usually use with the 27A. I even tried different inputs on the AVR300, but in all cases the noise was present until I disconnected the Sony from the AVR300.

I'm not particularly concerned with sound from the Sony & am happy to stick with toslink: we only use it for recording from VHS/OTA and for playback of kids' videos directly to the display anyway. (If the 27A was the cause, it'd be a different story...)

[pyro2003]

Hi there

I'm getting similar random static noise from my AVR300 when I set it up last nite, maybe it is also my coaxial digital cable .. (I hope; I'll verify tonite). But, tvh3ad, once you disconnect the Sony, are analogue sources fine by then ? My version of the noise is very disturbing like random static / clicking noise, and since my speakers go to 60 KHz, they're very loud and reverberating

Another problem I seem to be having is that the unit does not sync with other components very well over SPDIF, this goes for my Marantz DV9500 as well as my HTPC (running a proven USB transcoder to toslink, Maudio Transit)
The system seems to get intermittent sync often, so sound comes in and out, very annoying

Originally Posted by tvh3ad

I thought of that, but in this case I'm pretty sure it's the Sony unit itself. The original cable was a monster digital coax, and I also tried swapping it with the bluejeans coax I usually use with the 27A. I even tried different inputs on the AVR300, but in all cases the noise was present until I disconnected the Sony from the AVR300.

I'm not particularly concerned with sound from the Sony & am happy to stick with toslink: we only use it for recording from VHS/OTA and for playback of kids' videos directly to the display anyway. (If the 27A was the cause, it'd be a different story...)

[roffe]

Originally Posted by Hifi addict

try using a other or "better" coax cable. I guess your cable's ground is short circuiting everything. A good cable should have the ground only connected to 1 connector and not both to overcome this issue.

Most coax-cables have no extra shielding. The topology of the coax acts as shielding (the shield is also a conductor, and connecting it in only one end will give no proper signal).
Make sure you are using a real 75ohm coax, and not an ordinary shielded signal cable for analogue audio (although it may work in some setups).

[tvh3ad]

The Sony was definitely a major noise source. However, I never could get the AVR300 to be completely quiet (on any input). I finally gave up on it and am taking delivery of an AV9 tomorrow.

[pyro2003]

taking my trusty coaxial cable out did stop all the clicking noises. These were not ultra-expensive but very good quality 75Ohm cables that have served me for years on many different machines


with the coaxial cable out, I have proved to myself that the toslink digital input of the Arcam has some serious issues. Basically the unit will sync to the 96Khz PCM stream and play it sometimes. At others, it will play for 5 minutes or so and stop. At which point, the machine is frozen. No input buttons can touch it for a long long time, usually the power off button will be effective after a while

The next one is worse, in the frozen state, when I pull out the toslink, the unit power itself off.

I have a variety of AV prepro /amps (Yamaha, Denon, Onkyos, Sony ES, Proceed AVP2), this Arcam AVR300 is definitely the most unreliable unit I've experienced so far

More testing with my other digital sources tonite ...